This invention relates to a system and method of protecting against rollover in a motor vehicle.
Dynamic control systems have been recently introduced in automotive vehicles for measuring the body characteristics of the vehicle and controlling the dynamics of the vehicle based on the measured body characteristics. For example, certain systems measure vehicle characteristics to prevent vehicle rollover and for tilt control (or body roll). Tilt control maintains the vehicle body on a plane or nearly on a plane parallel to the road surface, and rollover control maintains the vehicle wheels on the road surface. Certain systems use a combination of yaw control and tilt control to maintain the vehicle body horizontal while turning. Commercial examples of these systems are known as active rollover prevention (ARP) and rollover stability control (RSC) systems.
The spectrum of conditions that may occur during the operation of the vehicle is too large to be practically evaluated during the development and production of the vehicle. As a result, the tuning of the rollover stability control system for the vehicle is typically performed with an extreme roof load to provide sufficient confidence that the system will perform suitably over road conditions that the vehicle will experience when being driven.
However, when the rollover stability control system is tuned in the roof-loaded condition, the gains are higher than those that would result from tuning in the normal-loaded condition. Thus, the system becomes very sensitive to small disturbances.
Moreover, conventional systems consider the longitudinal vehicle dynamics to estimate the mass of the system. Hence, these systems do not provide an indication about the way the mass is distributed with respect to the roll axis (i.e., the roll moment of inertia).